1840 is considered a watershed year in the history of New Zealand: The Treaty of Waitangi is signed, British sovereignty over New Zealand is proclaimed, organised European settlement begins, and Auckland and Wellington are both founded.
3 January — The Cuba arrives in Port Nicholson with a survey party to prepare for the New Zealand Company settlement.[9]
22 January — The first shipload of New Zealand Company immigrants arrives in Wellington on the Aurora and lands at Petone, which they name Britannia.[10]
6 February — Hōne Heke is the first to sign the Treaty of Waitangi at the Bay of Islands.[11]
19 February — French settlers under the command of Captain C. Lavaud, unaware of the Treaty of Waitangi, depart France in the L’Aube on their way to Akaroa.[12] (see 1838)
— Johnny Jones sends the first settlers (as opposed to whalers or sealers) to the South Island. They land from the Magnet and settle behind Cornish Head at Waikouaiti.[13]
6 April — George Clarke is appointed Protector of Aborigines by Governor Hobson.[14]
18 April — The New Zealand Gazette and Britannia Spectator prints its second issue in Britannia, becoming the first newspaper published in New Zealand. The first issue was printed in England the previous year. The paper publishes weekly, changing its name to The New Zealand Gazette and Wellington Spectator a few months later.[15]
21 May — Governor Hobson proclaims British sovereignty over New Zealand.
May
— First capital established at Okiato, which was at the time named Russell.
— Reverend James Watkin, sent by Johnny Jones, arrives at Waikouaiti and starts the first mission in the South Island.[13]
16 June — HMS Herald, Captain Joseph Nias, arrives at Port Underwood with Major Thomas Banbury to obtain signatures from southern chiefs to the Treaty of Waitangi. The final signatures are added the next day.[18][19] Later in the month the Herald arrives in Stewart Island where Banbury formally takes possession of the island in the name of Queen Victoria.[20]
— After discovering their original site is prone to flooding, the Wellington settlers move around the harbour to Thorndon, the site of the present city.[10]
20 October — 3,000 acres (12 km2) is purchased from local Ngāti Whātua chiefs for the Auckland settlement.[23]
^Statistics New Zealand has collated estimates from a number of sources (extrapolating where necessary) at "Long-term data series". Archived from the original on 5 March 2008. Retrieved 14 March 2008., in particular "A1.1 Total population.xls". Archived from the original(Excel) on 5 March 2008. Retrieved 14 March 2008.